Leo Has $12 $3 c+3 s \leq a$ B) $0.65 s+0.85 c+0.5 a \geq 12.5$

Leo has $12.50 to spend on his weekly supply of sweets, crisps and apples. A bag of crisps costs $0.65, a bag of sweets costs $0.85, and one apple costs $0.50. The total number of packets of crisps, sweets and apples consumed in a week must be at least seven, and he eats at least twice as many packets of sweets as crisps. His new healthy diet also means that the total number of packets of sweets and crisps must not exceed one- third of the number of apples. If s, c and a, denote the number of packets of sweets, packets of crisps, and apples respectively, which one of the following represents one of the constraints defining the feasible region?

A) $3 c+3 s \leq a$
B) $0.65 s+0.85 c+0.5 a \geq 12.5$
C) $s \geq 0.5 c$
D) $a+c+s>7$
E) $s \leq c-a$