Task: Question Answering
Input (English): Problem: in the xy - coordinate plane , the graph of y = - x ^ 2 + 4 intersects line l at ( p , 5 ) and ( t , - 7 ) . what is the least possible value of the slope of line l ? 
Options: a ) 6 , b ) 2 , c ) - 4 , d ) - 6 , e ) - 10
Output (English): c