Assertion : Type 'O' blood group individuals are called universal donors
Reason : RBCs of 'O' blood group have both 'A' and 'B' surface antigens.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion
B. If both assertion and reason are true but reason is not the correct explanation of assertion
C. If assertion is true but reason is false
D. If both assertion and reason are false

Explanation

To solve the question regarding the assertion and reason about blood group 'O', let's break it down step by step.

### Step 1: Understand the Assertion
The assertion states that individuals with type 'O' blood group are called universal donors. This is a widely accepted fact in blood transfusion science.

### Step 2: Understand the Reason
The reason provided is that RBCs (red blood cells) of 'O' blood group have both 'A' and 'B' surface antigens. To analyze this, we need to know what antigens are present in different blood groups.

### Step 3: Review Blood Group Characteristics
- **Blood Group A**: Has A antigens on RBCs and anti-B antibodies in plasma.
- **Blood Group B**: Has B antigens on RBCs and anti-A antibodies in plasma.
- **Blood Group AB**: Has both A and B antigens on RBCs and no antibodies in plasma.
- **Blood Group O**: Has no A or B antigens on RBCs but has both anti-A and anti-B antibodies in plasma.

### Step 4: Analyze the Reason
From our review, we see that type 'O' blood group does not have any A or B antigens on its RBCs. Therefore, the statement that RBCs of type 'O' have both A and B surface antigens is incorrect.

### Step 5: Conclusion
Since the assertion is true (type 'O' is indeed a universal donor) and the reason is false (type 'O' does not have A or B antigens), we conclude that the assertion is correct but the reason is incorrect.

### Final Answer
- **Assertion**: True
- **Reason**: False