Let us arrange people in decreasing order of heights:
By looking at each observation, we fill these stars $:*,*,*,*,*,*$ where the left-most star corresponds to the tallest person and the rightmost star corresponds to the shortest person.
- $\text{S}$ is taller than $\text{R}.$
So, $\text{S}>\text{R}$
- $\text{Q}$ is the shortest of all.
So, we have
$*,*,*,*,*,\text{Q}$
- $\text{U}$ is taller than only one student.
So, $\text{U}$ is second tallest. Hence,
$*,*,*,*,\text{U},\text{Q}$
- $\text{T}$ is taller than $\text{S}$ but not tallest.
$\text{T}$ is taller than $\text{S}$ implies $T> S$.
From observations $i$ and $iv,$ we have $\text{T}>\text{S}>\text{R}.$
Thus, we have one of these possibilities:
- $*,\text{T},\text{S},\text{R},\text{U},\text{Q}$ or
- $\text{T},*,\text{S},\text{R},\text{U},\text{Q}$ or
- $\text{T},\text{S},*,\text{R},\text{U},\text{Q}$ or
- $\text{T},\text{S},\text{R}*,\text{U},\text{Q}$
But it is mentioned that $\text{T}$ is not the tallest person.
So we are left with only one possibility:
$*,\text{T},\text{S},\text{R},\text{U},\text{Q}$
Since, we have only one student $\text{P}$ left, we fill the blank with $\text{P}$
$\text{P},\text{T},\text{S},\text{R},\text{U},\text{Q}$
- Number of students taller than $\text{R}=3$ $(\text{P},\text{T},\text{S})$
- Number of students shorter than $\text{T}=4$
- Number of students shorter than $\text{R}=2$
- Number of students shorter than $\text{S}=3$
Hence, option C is the correct answer.