Question: In the 10th Century A.D. Ealhswith had a son called Æthelweard by which English king?

full_context: Document 1: Eadric, Ealdorman of Wessex: Eadric (fl. 942–949) was a tenth-century ealdorman of Wessex. He was the youngest of four sons of Æthelfrith, an ealdorman in Mercia, and his wife Æthelgyth. From 946 until his death in 949 Eadric was the second most senior ealdorman in England, surpassed only by his brother Æthelstan Half-King.
Document 2: Ælfgar, Earl of Mercia: Ælfgar (died c. 1060) was the son of Leofric, Earl of Mercia, by his famous mother Godgifu (Lady Godiva). He succeeded to his father's title and responsibilities on the latter's death in 1057. He gained the additional title of Earl of East Anglia, but also was exiled for a time. Through the first marriage of his daughter he would become father-in-law of the Welsh king Gruffydd ap Llywelyn; a few years after his death, his daughter would become a widow and marry English King Harold.
Document 3: Ealhswith: Ealhswith or Ealswitha (died 5 December 902) was the wife of King Alfred the Great. Her father was a Mercian nobleman, Æthelred Mucel, Ealdorman of the Gaini, which is thought to be an old Mercian tribal group. Her mother was Eadburh, a member of the Mercian royal family, and according to the historian Cyril Hart she was a descendant of King Coenwulf of Mercia. She is commemorated as a saint in the Christian East and the West on July 20.
Document 4: Æthelfrith of Mercia: Æthelfrith (fl. 880s – c. 904/915) was an ealdorman of southern Mercia, who flourished in the last two decades of the ninth century and the first decade of the tenth century. His father is unknown. He was married to Æthelgyth, daughter of Æthelwulf; Æthelwulf is unidentified, but a possible candidate is King Alfred the Great's brother-in-law, the ealdorman of the Gaini who died in 901. Æthelfrith was father to four ealdormen: Æthelstan Half-King (East Anglia), Ælfstan (Mercia), Æthelwald (Kent), and Eadric (Hampshire).
Document 5: Ælfwynn: Ælfwynn was the ruler of Mercia for a few months in 918, following her mother's death. She was the daughter of Æthelred, ruler of English Mercia, and Æthelflæd (styled The Lady of Mercia). Following the death of her mother on 12 June 918, Ælfwynn was for a short time ruler of Mercia. The "Anglo-Saxon Chronicle" states that she was "deprived of all control in Mercia, and was led into Wessex three weeks before Christmas".
Document 6: Ealdgyth (floruit 1015–1016): Ealdgyth (circa 992 – after 1016), modern English Edith may have been the name of the wife of Sigeferth son of Earngrim, thegn of the Seven Burghs, and later of King Edmund Ironside. She was probably the mother of Edmund's sons Edward the Exile and Edmund Ætheling.
Document 7: Cynethryth: Cynethryth ("Cyneðryð"; died after AD 798) was a Queen of Mercia and wife of King Offa of Mercia and mother of King Ecgfrith of Mercia. Cynethryth is the only Anglo-Saxon Queen consort in whose name coinage was definitely issued.
Document 8: Æthelberht, King of Wessex: Æthelberht (or Ethelbert; Old English: "Æþelberht" , meaning "magnificent noble") was the King of Kent from 858 and of Wessex from 860 until his death in 865. He was the third son of Æthelwulf of Wessex and his first wife, Osburh. In 855 he became under-king of Kent while his father, Æthelwulf, visited Rome. His brother Æthelbald was left in charge of the West Saxons. After his father's death in 858 he succeeded him as king of Kent and the other eastern parts of the kingdom. When Æthelbald died childless in 860, the kingship of the West Saxons also passed to Æthelberht.
Document 9: Beorhtweald Ealdorman of Kent: Beorhtweald Ealdorman of Kent was an English ruler of the 9th Century AD. His father was Burgred of Mercia, his mother: Æthelswith, and his brother,: Beorhtnoð æthling of Kent.
Document 10: Ælfhere, Ealdorman of Mercia: Ælfhere (died in 983) was ealdorman of Mercia. His family, along with those of Æthelstan Half-King and Æthelstan Rota, rose to greatness in the middle third of the 10th century. In the reign of Edward the Martyr, Ælfhere was a leader of the anti-monastic reaction and an ally of Edward's stepmother Queen Dowager Ælfthryth. After the killing of Edward by Ælfthryth's servants in 978, Ælfhere supported the new king, Ælfthryth's son Æthelred the Unready, and was the leading nobleman in the Kingdom of England until his death in 983.
Document 11: Ealdgyth, daughter of Earl Ælfgar: Ealdgyth ("fl. c". 1057–1066), also Aldgyth or in modern English, Edith, was a daughter of Ælfgar, Earl of Mercia, the wife of Gruffudd ap Llywelyn (d. 1063), ruler of all Wales, and later the wife and queen consort of Harold Godwineson, king of England in 1066. She was described by William of Jumièges as a considerable beauty.
Document 12: Æthelred the Unready: Æthelred II, also dubbed the Unready (Old English: Æþelræd, ] ), (  966 – 23 April 1016) was King of the English (978–1013 and 1014–1016). He was the son of King Edgar the Peaceful and Queen Ælfthryth and was around 12 years old when his half-brother Edward the Martyr was murdered on 18 March 978. Although Æthelred was not personally suspected of participation, the murder was committed at Corfe Castle by his attendants, making it more difficult for the new king to rally the nation against the military raids by Danes, especially as the legend of St Edward the Martyr grew.
Document 13: Æthelwulf: Æthelwulf (Old English for "Noble Wolf"; died 13 January 858) was King of Wessex from 839 to 858. In 825, his father, King Egbert, defeated King Beornwulf of Mercia, ending a long Mercian dominance over Anglo-Saxon England south of the Humber. Egbert sent Æthelwulf with an army to Kent, where he expelled the Mercian sub-king and was himself appointed sub-king. After 830, Egbert maintained good relations with Mercia, and this was continued by Æthelwulf when he became king in 839, the first son to succeed his father as West Saxon king since 641.
Document 14: Æthelweard (son of Alfred): Æthelweard (d. 920 or 922) was the younger son of King Alfred the Great and Ealhswith.
Document 15: Edward the Elder: Edward the Elder (Old English: "Eadweard cyning "; c. 874 – 17 July 924) was King of the Anglo-Saxons from 899 until his death. He became king in 899 upon the death of his father, Alfred the Great. He captured the eastern Midlands and East Anglia from the Danes in 917 and became ruler of Mercia in 918 upon the death of Æthelflæd, his sister.
ground_truth: King Alfred the Great