Q: Answer the following question given this paragraph: Alloys can be one of two general types. In one type, called a substitutional alloy, the various atoms simply replace each other in the crystal structure. In another type, called an interstitial alloy, the smaller atoms such as carbon fit in between the larger atoms in the crystal packing arrangement. Q: Historically, malaria has rivaled what as the leading cause of human death by infectious disease? A:

Choices:
i. heart attack.
ii. hepatitis.
iii. cancer.
iv. tuberculosis.
A:
iv.