Among the following equations, which are linear
1. `2x+y-z=5`
2. `pix+y-ez=log3`
3. `3^(x)+2y=7`
4. `sinx-y-5z=4`
Select the correct answer using the code given below

Options

A. 1 only
B. 1 and 2 only
C. 3 and 4
D. 1, 2 and 4

Explanation

To determine which of the given equations are linear, we need to understand the definition of a linear equation. A linear equation in multiple variables can be expressed in the form:

\[ Ax + By + Cz + D = 0 \]

where A, B, C, and D are constants, and x, y, z are variables. The key characteristics of a linear equation are that the variables are only to the first power (no exponents, roots, or trigonometric functions) and they are not multiplied together.

Now, let's analyze each equation one by one:

1. **Equation: \( 2x + y - z = 5 \)**

This equation can be rearranged to the standard form:
\[ 2x + y - z - 5 = 0 \]
Here, the variables \( x, y, z \) are all to the first power, and it fits the linear equation format.

**Conclusion:** This is a linear equation.

2. **Equation: \( pix + y - ez = \log 3 \)**

Similar to the first equation, we can rearrange it:
\[ pix + y - ez - \log 3 = 0 \]
Again, the variables \( x, y, z \) appear only to the first power, and it fits the linear equation format.

**Conclusion:** This is also a linear equation.

3. **Equation: \( 3^x + 2y = 7 \)**

This equation involves \( 3^x \), which is an exponential function. Exponential functions are not linear because the variable \( x \) is in the exponent.

**Conclusion:** This is not a linear equation.

4. **Equation: \( \sin x - y - 5z = 4 \)**

The term \( \sin x \) is a trigonometric function, which is periodic and not linear. Thus, this equation does not fit the linear equation format.

**Conclusion:** This is not a linear equation.

Now, summarizing our findings:

- Linear equations: 1 and 2
- Non-linear equations: 3 and 4

Thus, the correct answer is that the linear equations among the given options are 1 and 2.

### Final Answer:
The linear equations are: 1 and 2.