answer is a.4

1 test case to check if system can read a and c
2 to check if a<10
3 to check if c is > 100 and < 100
to check if a and c are printed

two tests are required

Number of testcases required for branch coverage will be 2.

In branch coverage we need to check whether all the 
branches are exercised.
Here we have 3 branches all If statements we need to 
consider.They are A<10,C>100,C<100

Line 1 - Read(A,C)
Line 2 - If(A<10) then 
Line 3 - Print A;
Line 4 - Endif
Line 5 - If(C>100)then
Line 6 - Print C is greater then A
Line 7 - else if(C<100) then 
Line 8 - print C
Line 9 - End if

So take the values as follows
Testcase 1 : A=5 and C=120
For this set of values Line1 - Line6 are executed

Now for the Line7 - Line9 to be executed take the value of 
c as less than 100
So Testcase 2 : A=5(can be any value as Line 2,3,4 are 
already exercised in testcase1)and c=80
For this set of values Line7-Line9 will be exercised

Require 3 Path test cases.

Test Case 1 - A is any value > 9 and C = 100 to check that 
nothing is printed.

Test Case 2 - A is any value < 10 and C is > 100 to check 
that Print A and 
     Print C is greater than A lines are printed

Test Case 3 - A is any value, and C is < 100 to check that 
Print A ( only if A is < 10)
Print C is greater than A is printed. 

We should use Cyclomatic complexity formula to calculate 
number of paths easily 

 C = E - N + 2

Ans is 4 as there are two branches.For these two branches 
we need to test for both true & false conditions. hence to 
achieve 100% branch coverage we need to write 4 test cases.