$1.$ Which of the following is a type of supervised learning?

$$ a$)$ K$-$means clustering

$$ b$)$ Principal Component Analysis $($PCA$)$

o c$)$ Linear Regression

$$ d$)$ Autoencoders

$2.$ Which metric is commonly used for evaluating classification models?

$$ a$)$ Mean Squared Error $($MSE$)$

$$ b$)$ R$-$squared

$$ C$)$ Accuracy

$$ d$)$ Silhouette Score

$3.$ In the context of neural networks, what does the term "backpropagation" refer to$?$

$$ a$)$ A method for initializing weights

$$ b$)$ A technique for regularizing models

$$ c$)$ An algorithm for updating weights

$$ d$)$ A way to split data into training and test sets

$4.$ Which of the following is not a feature scaling technique?

$$ a$)$ Min$-$Max Scaling

$$ b$)$ Standardization

$$ c$)$ One$-$Hot Encoding

$$ d$)$ Normalization

$5.$ What is the main purpose of the validation set in machine learning?

$$ a$)$ To train the model

$$ b$)$ To test the final model performance

$$ c$)$ To tune the hyperparameters