Suppose a is a 4 x 7 matrix such that rank(a = 4. which of the following is true? a. the rank of at is 3 b. the nullity of a^t is 0 c. ax 0 only has trivial solution d. the rows of a are linearly dependent columns of a are e. linearly independent

At a constant it will take one hour to travel 32 mi.at that speed it will take 1/2 hr to travel the remaining 16 mi.it will take 1+1/2 hr to travel the 48mi @ 32mph.so 1 hr = 60 min& 1/2 hr = 30 min1+1/2 hr = 90 min.there are 60s in each 90 × 60 = 3600 seconds.the real question seriously is he why are they driving so slow? ! lol.