Step 1: Find the value of A.
For Normal students:
\[
\text{Percentage}
=
\frac{320}{800}\times 100
\]
\[
=40\%
\]
Therefore,
\[
{A=40}
\]
Step 2: Find the value of B.
For Vitamin A Deficiency:
\[
\text{Percentage}
=
\frac{120}{800}\times100
\]
\[
=15\%
\]
Hence,
\[
{B=15}
\]
Step 3: Find the value of C.
For B-complex Deficiency:
\[
\text{Percentage}
=
\frac{160}{800}\times100
\]
\[
=20\%
\]
Thus,
\[
{C=20}
\]
Step 4: Determine \(a\) and \(b\).
The table itself gives:
\[
\text{B-complex Deficiency}=160
\]
Therefore,
\[
{a=160}
\]
Similarly,
\[
\text{Anaemia}=200
\]
Hence,
\[
{b=200}
\]
Step 5: Calculate \(a_1\).
\[
a_1
=
\frac{160}{800}
\]
\[
=0.20
\]
Therefore,
\[
{a_1=0.20}
\]
Step 6: Calculate \(b_1\).
\[
b_1
=
\frac{200}{800}
\]
\[
=0.25
\]
Thus,
\[
{b_1=0.25}
\]
Step 7: Verify Statement (i).
Statement (i):
\[
A=40,\quad B=15,\quad C=20,
\]
\[
a=160,\quad b=200
\]
All values are correct.
Therefore,
\[
{\text{Statement (i) is correct}}
\]
Step 8: {Verify Statement (ii).}
Statement (ii) claims:
\[
a=100
\]
But actual value is
\[
a=160
\]
Hence,
\[
{\text{Statement (ii) is incorrect}}
\]
Step 9: {Verify Statement (iii).}
Statement (iii):
\[
A=40,\quad B=15,\quad C=20
\]
\[
a_1=0.20,\quad b_1=0.25
\]
All are correct.
Therefore,
\[
{\text{Statement (iii) is correct}}
\]
Step 10: {Verify Statement (iv).}
Statement (iv) claims:
\[
B=20,\quad C=15
\]
which is opposite to the actual values.
Hence,
\[
{\text{Statement (iv) is incorrect}}
\]
Step 11: {Final conclusion.}
The correct statements are:
\[
(i)\ \text{and}\ (iii)
\]
Therefore,
\[
{\text{Option (2)}}
\]